Fiber dyeing with a sulfuric acid ester of leuco vat dyestuff and an alkali metal nitrite

ABSTRACT

TEXTILE FABRIC, INCLUDING FABRIC OF MIXED CELLULOSE FIBERS AND POLYESTER FIBERS, ARE DYED WITH SUPERIOR RESULTS BY MEANS OF SALT OF SULFURIC ACID ESTER OF LEUCO VAT DYE BY TREATING (E.G. PADDING OR PRINTING) THE FIBROUS MATERIAL WITH AN AQUEOUS PREPARATION WHICH COMPRISES SALT OF SULFURIC ACID ESTER OF LEUCO VAT DYE AND ALKALI METAL NITRITE, BUT IS FREE FROM ACIDS AND ACID-YIELDING COMPOUNDS, AND THEN DEVELOPING AND FIXING THE THUS-TREATED FABRIC BY SOCALLED THERMO-FIXATION.

3,597,143 FIBER DYEING WITH A SULFURIC ACID ESTER CF LEUCO VAT DYESTUFF AND AN ALKALE METAL NlTRlTE Joseph Van Diest, Binningeu, Switzerland, assignor to Durand & Huguenin AaG Basel, Switzerland No Drawing. Filed Jan. 5, 1968, Ser. No. 695,870 Claims priority, application Switzerland, Jan. 5, 1967, 117/67 Int. Cl. D061: 3/82 US. Cl. 8-21 12 Claims ABSTRACT OF THE DISCLOSURE Textile fabric, including fabric of mixed cellulose fibers and polyester fibers, are dyed with superior results by means of salt of sulfuric acid ester of leuco yat dye by treating (e.g. padding or printing) the fibrous material with an aqueous preparation which comprises salt of sulfuric acid ester of leuco vat dye and alkali metal nitrite, but is free from acids and acid-yielding compounds, and then developing and fixing the thus-treated fabric by socalled thermo-fixation.

It is known that fibrous materials can be dyed with salts of sulfuric acid esters of leuco vat dyestuffs by treating the fibrous material with an aqueous solution of such a salt, and developing the dyeing, if desired at a raised temperature, by the action of an oxidizing agent, such as an alkali metal nitrite, chromate or chlorate, in the presence of an acid or a compound yielding an acid under the action of heat, for example, an ammonium salt. The developement may be carried out in a bath that contains the oxidizing agent and the acid. Alternatively, the oxidizing agent and a compound yielding an acid may be incorporated into the aqueous solution of the salt of the sulfuric acid ester. The development is then carried out subsequently by steaming or by a dry heat treatment. A process is also known that enables the dyeing to be developed without an oxidizing agent (see J. Miller, Melliand, 1957, page 1157). In this process the fibrous material is treated with an aqueous solution of a salt of a sulfuric acid ester of a leuco vat dyestuff, which solution may contain a compound yielding acid, and the material is then dried and heated in the dry state for a short time at a raised temperature, for example, at 200 C. In this case the vat dyestuff is oxidized by the action of the oxygen of the air.

None of the known processes for dyeing with salts of sulfuric acid esters of leuco vat dyestuffs enables mixed fabrics containing synthetic fibers, especially mixed fabrics of cellulose fibers and polyester fibers, to be dyed satisfactorily in all respects. The simultaneous action of oxidizing agents and compounds yielding acid often leads at high temperatures to impairment in the quality of the fibers and of the tint of the dyeing, which takes the form, for example, of a reduction in the tensile strength of the fibers or in dulling of the tint of the dyeing. If, on the other hand, the dyeing is carried out without an oxidizing agent the color yield, especially in dyeing fibrous materials of cellulose, is considerably reduced. Furthermore, it is difficult in practice, due, among other things, to the close dependence of color yield upon the temperature used and the fact that oxidation with hot air is difiicult to control, to achieve a reproducible loss in color.

The present invention is based on the observation that fibrous materials can be dyed with salts of sulfuric acid esters of leuco vat dyestuffs by treating the fibrous material with an aqueous preparation which comprises a salt of a sulfuric acid ester of a leuco vat dyestuff and nited States Patent an alkali metal nitrite and is free from acids, and compounds yielding acid, drying the treated material, and heating it for a short time at a raised temperature.

By the process of this invention a Wide variety of fibrous materials can be dyed, for example, in the form of hanks, fabrics, knitted goods or the like and composed of natural fibers, such as cotton, linen or silk, or of semi-synthetic fibers, such as viscose silk or staple fibers of regenerated cellulose, or of synthetic fibers, such as linear polyesters, polyamides, polyacrylonitrile, and also mixtures of the aforesaid fibers. The process is more especially suitable for dyeing mixtures of polyester fibers and cellulose fibers.

As salts of sulfuric acid esters of leuco vat dyestuffs there are used those that are soluble in Water. Mixtures of salts of sulfuric acid esters of different leuco vat dyestuffs can be used with the same good results. As the alkali metal nitrite there is advantageously used sodium nitrite but other compounds of this class, e.g. potassium nitrite, can also be used.

As the aqueous preparations there may be mentioned printing pastes, but more especially padding baths. The usual dyeing assistants may be incorporated With the preparations. Such assistants are, for example, wetting agents, thickening agents, migration inhibitors, final uniformity agents, substances that influence the affinity and solubility of the dyestuffs, agents that inhibit over-oxidation, and alkalies. The preparations may, if desired, also contain other dyestuffs, for example, dispersion dyestuffs.

The development and fixing of the salts of sulfuric acid esters of leuco vat dyestuffs may be carried out under the usual conditions of thermo-fixation, that is to say, by a dry heat treatment for a period ranging from about 5 seconds to 5 minutes at a temperature ranging from about 170 C. to 240 C. In the case. of mixtures of different fibers the development and fixing take place simultaneously and uniformly on all types of fibers.

The process of this invention enables fibrous materials, especially mixtures of polyester fibers and cotton fibers, to be dyed in a simple manner uniformly and reproducibly With high color yields and without impairment of the quality of the fibers or the tint of the dyeing.

The following examples illustrate the invention, the percentages being by weight, the parts being by weight unless otherwise stated, and the relationship of part by weight to part by volume being the same as that of the kilogram to the liter.

EXAMPLE 1 A mercerized cotton fabric was padded with the squeezing effect of about 60% in a padding bath, which contained 10 parts of the dyestuff CI. 60531 (Colour Index, vol. 3, 1956), parts of urea, 30 parts of an aqueous solution of 5% strength of the sodium salt of polymeric methacrylic acid, 1 part of ethylene oxide alkyl-phenol addition product, 1 part of a condensation product of a fatty acid and degraded albumin, 10 parts of sodium nitrite and 850 parts of Water. The fabric was dried and subected to a dry heat treatment at 210 C. for 1 minute. The fabric was then soaped at the boil and finished in the usual manner.

There was obtained a yellow dyeing that had a considerably greater color strength than a dyeing produced with a padding bath that contained 5 parts of ammonium sulphate, instead of 10 parts of sodium nitrite.

The same good result with respect to depth of color was obtained with the dyestuffs C.I. 59826, C.I. 73336 and CI. 59101.

By using, instead of the mercerized cotton fabric, a viscose fabric and 10 parts of the dyestuff CI. 60011 and '3 a 200 parts of urea, there was obtained a deep violet dye- EXAMPLE 2 A fabric of polyethylene terephthalate fibers was padded with a squeezing effect of about 60% in a padding bath having the same composition as that described in Example 1, except that it contained 10 parts of the dyestuif CI. 73366, instead of the dyestufi (1.1. 60531. The fabric was dried and subjected to a dry heat treatment at 220 C. for 1 minute. The fabric was then soaped at the boil and finished in the usual manner. There was obtained a strong pink dyeing.

By using the dyestuif CI. 59101, instead of the dyestuff CI. 73366, there was obtained a strong brilliant yellow dyeing.

EXAMPLE 3 A mixed fabric of polyethylene terephthalate fibers and cotton fibers (67/33) was dyed by the process described in Example 1. There was obtained a uniform yellow dyeing which was considerably more vivid than a dyeing produced in known manner with the use of sodium chlorate and ammonium sulfate.

EXAMPLE 4 50 parts of the dyestuif CI. 73336 and 200 parts of urea were dissolved in 200 parts of boiling water. To this solution were added 500 parts of sodium alginate thickener prepared ready for use, 9 parts of sodium nitrite and 20 parts of a 2 N-solution of sodium carbonate in. water. A cotton fabric was printed with the resulting preparation. After being dried, the printed fabric was thermofixed at 200 C. for 1 minute, then rinsed and finished. There was obtained a strong orange print.

By using in this example, instead of the dyestufi CI. 73336, 50 parts of the dyestuif C.I. 73601, and printing the preparation on a fabric of polyethylene terephthalate fibers, there was obtained a deep violet dyeing.

Mixed fabrics of polyethylene terephthalate fibers and cotton fibers were uniformly printed with the same success by the process described in this example.

EXAMPLE 5 parts of the dyestufi C.I. 69826, 30 parts of an aqueous solution of 5% strength of the sodium salt of polymeric methacrylic acid, 2 parts of ethylene oxide alkylphenol addition product and 10 parts of sodium nitrite were dissolved in water. The solution was then diluted with water to 1000 parts by volume. The resulting padding bath was used to dye a mixed fabric of polyethylene terephthalate fibers and cotton fibers (67/33) by the process described in Example 1. There was obtained a pure and strong blue dyeing.

(3.1. 60531 (Solubilized Vat Yellow 7) is the leuco sulfuric ester of 4. CI. 59826 (Solubilized Vat Green 1) is the leuco sulfuric ester of Q 2 t Q moo 0011 3 ((1.1. ssszs) CI. 73336 (Solubilized Vat Orange 5) is the leuco sulfurie ester of CI. 59101 (Solubilized Vat Yellow 4) is the leuco sulfuric ester of CI. 60011 (Solubilized Vat Violet l) is the leuco sulfuric ester of CI. 73601 (Solubilized Vat Violet 8) is the leuco sulfuric ester of furic ester of EN ll 0 l 0 it NH ll O (0.1. 00825) All the esters are used in the sodium salt form.

What is claimed is:

1. In a process for dyeing fibrous material with watersoluble salt of sulfuric acid ester of leuco vat dyestuff, the improvement according to which the fibrous material is treated with an aqueous preparation, which consists essentially of a water soluble salt of sulfuric acid ester of leuco vat dyestufi' and alkali metal nitrite, the treated material is dried, and the dyeing then subjected to thermofixation in a dry heat treatment for a short time at 170 C. to 240 C.

2. The improvement according to claim 1, wherein the fibrous material is mercerized cotton fabric.

3. The improvement according to claim 1, wherein the fibrous material is polyethylene terephthalate fabric.

4. The improvement according to claim 1, wherein the fibrous material is a mixed fabric of polyethylene terephthalate fibers and cotton fibers.

5. The improvement according to claim 1, wherein the fibrous material is cotton fabric.

6. The improvement according to claim 1, wherein the thermo-fixation is a dry heat treatment for about 5 seconds to 5 minutes at 170 to 240 C.

7. The improvement according to claim 1, wherein the fibrous material is applied by padding.

8. The improvement according to claim 1, wherein the fibrous material is applied by printing.

9. The improvement according to claim 1, wherein the alkali metal nitrite is sodium nitrite.

10. A process according to claim 1, wherein the watersoluble salt of sulfuric acid ester of leuco vat dyestufl is the sodium salt.

11. A process according to claim 10, wherein the fiber to be treated is a mixture of polyester fibers and cellulose fibers.

12. A process according to claim 10, wherein the alkali metal nitrite is sodium or potassium nitrite.

References Cited UNITED STATES PATENTS 8/1946 Clark 835X 12/1947 Ratti et al. 835X US. Cl. X.R. 

